Studies of the production of lipoproteins are important because lipoproteins are involved in the lipid metabolism of virtually all cells, and disorders of lipid transport contribute importantly to atheroscleosis. Therefore, an understanding of the normal processes of production and the factors which influence them could contribute to an understanding of human pathophysiology and to the design of rational modes of therapy. One of the major aims of this project is to study the effects of hormonal metabolic perturbations on the rates of secretion and on the structures and compositions of the lipoproteins secreted by perfused rat livers. Changes in secretory patterns can point to possible sites of control in intracellular synthesis and/or assembly. Another major aim is to study the synthesis of apoproteins. Human small intestine and liver obtained at surgery, and human small intestinal biopsies, as well as tissues of the rat will be studied. Techniques of immunolocalization, immunoprecipitation, and immunoassay will be employed to identify factors which alter the intracellular localization and biosynthesis of individual apoproteins and to ascertain whether and to what extent the synthesis of apoproteins and lipids is integrated. Results of the studies of secrtory patterns will be compared to studies of biosynthesis in the hope that the latter may help to explain the former.